Nemathelminthes Gegenbaur, 1859 see Phylum Nematoda Gegenbaur, 1859
   Class Nematoda Gegenbaur, 1859
     Subclass Secernentia (Von Linstow, 1905) Andrássy, 1976
       Order Rhabditida Chitwood, 1933
         Suborder Rhabditina Chitwood, 1933
           22 Family Rhabditidae Örley, 1880
           23 Family Alloionematidae Chitwood & McIntosh, 1934
           24 Family Diploscapteridae Chitwood & Chitwood, 1937
           25 Family Bunonematidae Micoletzky, 1922